The alkylation of aromatic amines by the reaction of the aromatic amine with an olefin in the presence of a catalyst system is known. Patents which illustrate aromatic amine alkylation processes using a heterogeneous catalyst system comprising silica-alumina catalysts are as follows:
British Patent No. 421,791 discloses the reaction of N-alkylated aromatic amines to ring alkylated aromatic amines by effecting isomerization in the presence of activated hydrosilicates.
French Patent No. 1.406,739 discloses ring alkylation of aromatic amines and other aromatic compounds by contacting the aromatic amine with an olefin in the presence of a crystalline alumino-silicate. Aniline and diphenylamine are represented as examples of aromatic hydrocarbon suited for alkylation.
Canadian Patent No. 663,698 discloses para-alkylation of aromatic amines, typically aniline derivatives, by contacting aniline with an olefin in the presence of a silica-alumina-type catalyst. Anilineisobutylene reactions are carried out at temperatures from about 200.degree.-330.degree. C. with temperatures of 240.degree.-260.degree. C. being preferred.
U.S. Pat. No. 4,351,951 discloses a process for preparing aromatic amines by reacting the aromatic amine with the primary or secondary alcohol in the presence of a catalyst containing iron oxides.
British Patent No. 846,226 discloses a process for the alkylation of aniline and phenyl amines by reaction with isobutylene in liquid phase at temperatures between 150.degree. and 300.degree. C. in the presence of activated, substantially neutral bleaching earths of the montmorillonite type.
Lavroski, et al., in an article Catalytic Alkylation of Aniline by n-Butene shows the reaction of aniline with n-butene in the presence of a silica-alumina catalyst.
U.S. Pat. No. 2,194,079 shows the reaction of diphenylamine with cyclohexene in the presence of an acid-activated bleaching earth.